Unraveling the corrosion-mitigating action of cyclobenzaprine hydrochloride on carbon steel in acidic media: integrated experimental and multiscale molecular perspectives

Abstract

Abstract Using a combination of computational and experimental methods, the corrosion protection effectiveness provided by cyclobenzaprine (CBA) for carbon steel (CS) in a 1.0 M hydrochloric acid solution was systematically examined. The corrosion protection efficiency and electrochemical behavior of CS with and without different concentrations of CBA were assessed using gravimetric measurements, polarization studies, impedance measurements, and the evaluation of the open circuit potential. The addition of CBA resulted in a notable decrease in double-layer capacitance (C dl ) and an increase in charge transfer resistance (R ct ), a considerable increase in the relaxation time constant (τ), as well as a considerable decrease in corrosion rate and corrosion current density, according to gravimetric and electrochemical data. The formation of a surface-bound shielding layer on the CS was demonstrated by surface characterization using SEM/EDS, AFM analysis, wettability assessment via contact angle evaluation, and UV–visible spectroscopic examination. At 192 μmol L −1 , the most effective corrosion protection of ~ 96% was achieved. The results showed that CBA functioned as an effective mixed-type inhibitor. Predominant physical adsorption was indicated by the corrosion inhibition efficiency, which improved with higher inhibitor dosage but decreased as the temperature rose. The thermodynamic and kinetic analyses showed spontaneous adsorption, following the Langmuir isotherm. The electronic characteristics and active adsorption centers of CBA were elucidated through density functional theory calculations, Fukui function examination, and natural bond orbital investigation. Additionally, the significance of π–electron systems and heteroatoms in surface interactions was emphasized.